The present invention relates to micro-machined relays, and more specifically to micro-machined relays that separate the gate voltage from the source voltage.
Relays are used in circuit design to provide a true switch having two states: completely-on and completely-off. This type of switch is in direct opposition to MOS based switches that have a voltage region in which the switch is partially on or partially off. Relays provide the benefit of a low-on resistance and a high-off resistance, whereas MOS based switches leak current and have a high-on resistance.
A micro-machined relay includes a source, drain, a conductive beam structure, and a gate. The micro-machined relay closes when a potential between the beam structure and the gate creates an electrostatic force that bends the beam so that the source and drain are electrically connected. In prior art micro-machined relays, the closure voltage was tied to the signal voltage. For example, if 30V were required to make a firm closure of the micro-machined relay, so that the signal can pass between the source and the gate and the signal voltage is + or −2V, the voltage applied to close the switch must be at least 32V. As signal voltages increase, for example to + or −15V, then the switch must be able to supply a voltage of 45V and can see a maximum voltage of 60V. In a micro-machined relay structure, this amount of voltage can break the beam of the relay.